What NAV aids are used on an aircraft?

aircraft tech trng

Just something I put together to give a brief discription of modern NAV aids used on a commercial aircraft such as 777. As you see there are 11 means of navigation used which assist the pilot in take off, cruise & landing

1 The VHF omnidirectional ranging (VOR) system is a navigation aid that gives magnetic bearing data from a VOR ground station to the airplane.The VOR ground stations transmit an omnidirectional signal and directional signal. Together the signals give magnetic radial information from 000 degrees to 359 degrees. All VOR stations reference the 000 degree to magnetic north. The VOR system receives the ground station signals and calculates bearing data. The data goes to various systems for display and navigation use. The VOR system supplies station audio and identifier signals to the flight deck speakers and headsets.

2 The ILS function provides lateral and vertical guidance to the runway on approach. The system uses signals from a glideslope ground station and a localizer ground station. The glideslope station transmits signals to give the airplane a descent path to the touchdown point on the runway. The localizer station transmits signals to give a lateral path to keep the airplane centered on the runway.
The ILS system provides station audio and identifier signals to the flight interphone speakers and the headsets.

3 The distance measuring equipment (DME) system supplies slant range (line of sight) distance between the airplane and the ground station. The DME system supplies station audio and identifier signals to the flight interphone speakers and headsets.

4 The automatic direction finder (ADF) system is a navigation aid. The ADF receiver uses AM signals from ground stations to calculate the bearing to the station from the airplane longitudinal axis, and to receive standard AM radio broadcasts. The marker beacon system supplies visual and aural indications when the airplane flies over marker beacon transmitters.

5 The purpose of the ground proximity warning system (GPWS) is to alert the flight crew of an unsafe condition when near the terrain. It also supplies a warning for windshear conditions.

6 The weather radar (WXR) system supplies:
- Visual indications of weather conditions
- Visual indications of land contours.
The WXR system transmits radio frequency (RF) pulses in a 180 degree sector forward of the airplane path.
Precipitation or terrain contours reflect the pulses back to the airplane. The WXR returns show in four different colors on the navigation displays (ND). The colors of the indications depend on the intensity of the returns.


7 The air traffic control (ATC) ground stations make interrogations of the airborne ATC/mode S transponder system. The ATC/mode S transponder makes replies to the interrogations as coded data that the ground station uses. The ground station uses a primary surveillance radar (PSR) to get radar returns from airplanes in the radar range. To make a communication link with the airplanes in the radar range, the ground station uses a secondary surveillance radar (SSR) to make interrogations of the ATC/mode S transponder. The ground station transmits a side lobe suppression signal to inhibit close ATC replies that come from an SSR side lobe transmission. On the ground radar display, the ATC operator sees the radar returns, altitude, and a four digit airplane identifier. The ATC operator sees airplane data from enhanced surveillance (EHS) on the ground station radar display

8 The traffic alert and collision avoidance system (TCAS) helps the flight crew and air traffic control maintain safe air traffic separation. TCAS is an airborne system. TCAS uses an air traffic control radar beacon system (ATCRBS) transponder or an ATC/Mode S transponder to track other airplanes. TCAS also coordinates maneuvers with other airplanes that have TCAS. TCAS supplies a traffic display and visual and aural vertical commands to the flight crew. All commercial airlines and some general aviation airplanes have TCAS.

9 The radio altimeter (RA) system measures the distance from the airplane to the ground. The radio altitude shows in the flight deck. The system has a range of -20 to 2500 feet. The flight crew and other airplane systems use radio altitude during approach and landing.


10 The standby magnetic compass is a backup magnetic heading reference.

11 The global positioning system (GPS) uses navigation satellites to supply accurate airplane position to airplane systems and to the flight crew.

Manic Moran

10 The standby magnetic compass is a backup magnetic heading reference.

Why mention that and not the HSI? (Although, granted, on older aircraft the HSI needs to be updated with reference to the compass).

After all, dead reckoning is a time-honoured part of navigation. Use your HSI, the airspeed indicator and your watch. No matter what your NavAid says, if you haven't sighted land an hour after you should have, you should have a clue that wherever you are, it's not where you should be!

I'm guessing sun compasses are no longer found on commercial aircraft?

NTM

aircraft tech trng

If a modern aircraft and such as the 777 lost all electrical power all you would be left with is the compass. The ISIS is your standby system with glideslope, ILS, heading etc but even they require electrical power where as most other means of navigation use the AIDRU (again electrical power). I do agree with you but technology has taken over with electronics and it is a shame.

aircraft tech trng

If you wish to go a little deeper have a look at the navigation section of

http://www.aircrafttechtrng.com/B777%20Gen%20Fam.pdf

Bearcat

small point.....isis uses standby electrical pwr.....subtle difference esp when u lose all your main sources of elec pwr as in IDG's and APU.

ADF's are becoming a thing of the past and an outdated mode in the US/Canada where Rnav approaches. Latest 777's/340's/330's etc dont come with ADF's unless requested as an optional extra.

IAA I am aware approving some Irish operators soon to use stand alone GPS Rnav approaches taking away any requirement for ADF's.

Stovepipe

Hi there,
It is still a requirement for a commercial or private aircraft carrying out Instrument Flight to have a functioning ADF. They're **** but they still have to be there.
regards
Stovepipe

Manic Moran

Interesting. I just rechecked the FAR/AIM for the US, there is no such requirement over here, and a good few owners have removed the ADF for some more useful instrument.

NTM

wittymoniker

Stovepipe wrote: »

Hi there,
It is still a requirement for a commercial or private aircraft carrying out Instrument Flight to have a functioning ADF. They're **** but they still have to be there.
regards
Stovepipe

not true, as stated many new aircraft anr not equipped with them at all.

balkanhawk

I believe an RNAV system allows the replacement of ADF in modern aircraft. it can use VOR, DME, INS and/or GPS to reference the NDB's position.

rob88

yea i noticed on new cockpits they don't have the non electrical basic instruments .. what happens if there is a power failure.. are the new ones run by a separate battery or something?

A320

Its wired to the Hot Battery Bus and DC ESS bus,the DC ESS bus being the normal supply to it,and directly from the battery bus as last resort as long as a/c speed greater than 50kts

Stovepipe

Hi there,
Well, all I can say is, it's still on the IR syllabus, NDB approaches and holds are still flown and ADFs are fitted to current A320s.The beast still lives!
regards
Stovepipe